MgB 2 and BSCCO S.I. SCHLACHTER, W. GOLDACKER KARLSRUHE INSTITUTE OF TECHNOLOGY, INSTITUTE FOR TECHNICAL PHYSICS KIT University of the State of Baden-Wuerttemberg and National Research Center of the Helmholtz Association www.kit.edu
Contents Situation for MgB 2 materials (commercial) and cables BSCCO(2223) cables BSCCO(2212) cables Conclusions 2 26/27.05.2011 Wilfried Goldacker HTS4Fusion WS KIT
Current carrying capability of LTC and HTS wires at lhe 3 26/27.05.2011 Wilfried Goldacker HTS4Fusion WS KIT
The interest in MgB 2 is better temperature margin than LTS, expected possible upgrade of transport currents and low costs!!! 30 20 Nb 3 Sn YBCO B irr [T] 10 NbTi Coils for Fusion Reactors Bi2223 MgB 2 0 LHe LH 2 LNe LN 2 pumped LN 2 0 20 40 60 80 100 Temperature [K] 4 26/27.05.2011 Wilfried Goldacker HTS4Fusion WS KIT
Examples of MgB 2 conductors for cables PIT manufactering in length exceeding 1 km (industry) HyperTech Research Inc., USA IEE, Bratislava Cu-30Ni Cu MgB 2 Nb Fe AgMg Nb Columbus Superconductors srl, Genoa: Karlsruhe Institute of Technology SS Fe SS SS Nb Fe Cu MgB 2 Cu Fe Ni Round wires are very suited for assembling cables, speciality of KIT are thin wires, down to 0.25 mm! 5 26/27.05.2011 Wilfried Goldacker HTS4Fusion WS KIT
Commercial availability of MgB 2 conductors I Columbus Superconductors srl, Genua Length: ~1-5 km Total Production: 2007: 100 km 2008: 300 km anticipated Standard: Ex-Situ 14 Filaments I c (A) 1000 100 10 tape 14 fil-perp wirea-19 fil wireb-19 fil wirec-19 fil wired-37 fil wiree-19 fil 1 T = 4.2 K 1 2 3 4 5 6 7 8 9 B (T) 6 26/27.05.2011 Wilfried Goldacker HTS4Fusion WS KIT
Commercial availability of MgB 2 conductors II HyperTech Res., Columbus Ohio Diameter 0.7-0.9 mm (and others) In-situ-route Filament number 7 and 19 (higher filament numbers experimentally) State Reacted and unreacted, insulated with s-glass Heat Treatment 700 C / 20 minutes (nominal) Critical Current Density, J c, A cm -2 10 6 NbCu19+M A (700-20) NbCu19+M C (700-20) NbCu19+M D (700-20) NbCu19+M E (700-20) NbCu19+M G (700-20) 10 5 NbCu19+M H (700-20) NbCu19+M I (700-20) NbCu19+M J (700-20) NbCu19+M M (700-20) NbCu19+M N (700-20) 10 4 10 3 J c @ 20 K 2T Max. axial strain tolerance Continuous length Superconductor fraction 175,000 A/cm 2 (nominal) 0.35% 1-4 km 13 18% (30% under development) 10 2 0 2 4 6 8 10 12 14 Magnetic Field, B, T At 4.2 K and 4 T: J c = 0.64-1.7 x 10 5 A cm -2 At 4.2 K and 8 T: J c = 0.42-1.3 x 10 4 A cm -2 http://www.hypertechresearch.com/ 7 26/27.05.2011 Wilfried Goldacker HTS4Fusion WS KIT
Coming to assembled wires: cable concepts 8 26/27.05.2011 Wilfried Goldacker HTS4Fusion WS KIT
MgB 2 Cables at FZK (Status): Possibilities: Continuous cabling Easy control of twist length Constant winding angle Constant strand tension Addition of Cu wires Cable & React Technology Cable & React (C&R) Technique High deformation of sc strands possible Small twist pitches J c,cable ~ J c,wire!!! J c [Acm -2 ] 10 6 10 5 10 4 10 3 10 2 Strand S2: MgB 2 /Nb/Cu/SS Cable C3: 3 x 1 Cable C4: 6 x 1 + Cu 0 1 2 3 4 5 6 7 8 9 10 11 B [T] 9 26/27.05.2011 Wilfried Goldacker HTS4Fusion WS KIT
Specialities of the KIT cable route Diversity of strands: Thin wires Different sheath composite SS-sheath SS-Nb-sheath In-situ Processing: Cabling of unreacted wires Allows very small twist pitch Flexibility of cable design Suitable for RTR (T < 640 C/ 10-20 min) No SS softening Suitable for Cu-strands SS-Cu-Nb-sheath 10 26/27.05.2011 Wilfried Goldacker HTS4Fusion WS KIT
MgB 2 cables at IEE Bratislava (P. Kovac et al SUST 23 (2010) 105006) The transport critical current density shows degradation at < 30-70 micron depending on composite design 1000 A! Also the transport current goes down with filament size, possibly due to geometry sausaging (PIT) and barrier defects 11 26/27.05.2011 Wilfried Goldacker HTS4Fusion WS KIT
Examples for MgB 2 cables at IEE Bratislava Institute for Electrical Engineering, Bratislava: I. Hušek et al., Cryogenics 49 (2009) 366 370 12 26/27.05.2011 Wilfried Goldacker HTS4Fusion WS KIT
MgB 2 cables R&D at CERN /Columbus: Survey busbar concepts for LHC upgrade (CERN) Design: (MgB 2 -conductors in green) Cable concepts : I = 3 ka I = 14 ka Copper mockups: I = 8 x 0.6 ka I = 7 x 14 ka I = 7 x 3 ka All 4.2K s.f. A. Ballarino, Proceedings EUCAS 2009, Dresden, 13.-17.9.2009 13 26/27.05.2011 Wilfried Goldacker HTS4Fusion WS KIT
Conclusions for MgB 2 Suitable so far for medium field range at lhe Limits for reaching small filaments (PIT) High potential for cabling, standard procedures Cheap wires, round wires Good choice for busbars Potential for much higher performance (Geneva!) Cables for >20 ka in magnetic field are very complex, not demonstrated so far! Wires are commercial! 14 26/27.05.2011 Wilfried Goldacker HTS4Fusion WS KIT
Contents Situation for MgB 2 materials (commercial) and cables BSCCO(2223) cables BSCCO(2212) cables Conclusions Tapes are commercial! 15 26/27.05.2011 Wilfried Goldacker HTS4Fusion WS KIT
ROEBEL bar (CTC) from BSCCO(2223) tapes (Siemens) M. Leghissa et al. Features: In-plane bending of tapes Transposition 2.5 3.4 m 1.18 ka at 77 K s.f. Insulated strands BSCCO(Ag/AgMg) 16 26/27.05.2011 Wilfried Goldacker HTS4Fusion WS KIT
Characteristics of CTC- BSCCO-cables (M.Leghissa SIEMENS) Transport AC losses explained assuming monobloc model Filament intergrowths Strong current degradation in self field Typical BSCCO tape (EAS) 17 26/27.05.2011 Wilfried Goldacker HTS4Fusion WS KIT
Strong filament coupling from intergrowths AC losses reduced via strand (tape) width! Strong current degradation in self field Characteristics of CTC- BSCCO-cables (M.Leghissa SIEMENS) Transport AC losses explained assuming monobloc model Filament intergrowths Typical BSCCO tape (EAS) 18 26/27.05.2011 Wilfried Goldacker HTS4Fusion WS KIT
Performance of BSCCO(2223) and REBCO Normalized Current I c (B,T)/I c (s.f.,77k) 10 1 0.1 0.01 66 K 77 K 50 K 77 K 4.2 K 4.2 K 65 K B Tape 22 K 20 K 50 K 0 2 4 6 8 10 12 B (T) Sumitomo DI-BSCCO 77 K 66 K 50 K 20 K 4 K SuperPower REBCO 77 K 65 K 50 K 22 K 4.2 K Sumitomo DI-BSCCO: http://global-sei.com/super/hts_e/type_h.html SuperPower REBCO: D. Hazelton et al., Recent Developments in 2G HTS Coil Technology - Talk 5LZ01, ASC 2010, Washington DC, Aug. 1-6, 2010 Y.-Y. Xie et al. ; 2009 KEPRI-EPRI Joint Superconductivity Conference, Nov 16-19, 2009 Daejeon, South Korea Better I c (B,T)-performance for REBCO-conductors than for BSCCO (2223) conductors for T 65-77 K BSCCO(2223) is definitly fixed to a tape structure which is limiting ideas for cable designs in particular with low AC loss structure 19 26/27.05.2011 Wilfried Goldacker HTS4Fusion WS KIT
Contents Situation for MgB 2 materials (commercial) and cables BSCCO(2223) cables BSCCO(2212) cables Conclusions 20 26/27.05.2011 Wilfried Goldacker HTS4Fusion WS KIT
Hasegawa T, et al. (2001), IEEE Trans. on Appl. Superc., 11, 3034 Strong bridging as result of I c optimization At low temperature the current carrying capacity of (2212) is superior to (2223) 21 26/27.05.2011 Wilfried Goldacker HTS4Fusion WS KIT
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Strand performance very sensitive depending on treatment and different filament size & number 23 26/27.05.2011 Wilfried Goldacker HTS4Fusion WS KIT
High current AC cable (2212) for accelarator magnets (BNL-Showa-Oxford-Nexans) 24 26/27.05.2011 Wilfried Goldacker HTS4Fusion WS KIT
Performance of (2212) Rurtherford cable (Showa electric) 25 26/27.05.2011 Wilfried Goldacker HTS4Fusion WS KIT
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BSCCO(2212) Rutherford cable (Korea) S.-C.Kim et al. Estimated current densities 5 K 0.1 T and (10 K 5T) 20 strands: 127 (15) kacm -2 30 strands: 110 (11) kacm -2 27 26/27.05.2011 Wilfried Goldacker HTS4Fusion WS KIT
BSCCO(2212) Rutherford Cable (OSU, BNL, IGC, Showa) E.W.Collings et al. Strand with 380 filaments Cables with varied strand coupling best cable current 3.5 ka 28 26/27.05.2011 Wilfried Goldacker HTS4Fusion WS KIT
BSCCO(2212) RF Cable, coupling losses for different designs E.W.Collings et al. Alternating NiCr cores cause low coupling Al 2 O 3 plasma-spraying is also insulating One of the rare R&D actions to work on technical issues and a more sophisticated cable design! Coupling losses (at Bm =400 mt) for cables Bi-NC (core of NiCr), Bi-AO-NC (NiCr-core and plasma-sprayed Al2O3 coating), BI-NC- NC (alternating 9 HTS, 9 NiCr strands) 29 26/27.05.2011 Wilfried Goldacker HTS4Fusion WS KIT
Summary for BSCCO Rutherford Cables Referenz HTS material I c (4.2K, s.f.) [A] * extrapolated ** at 77 K No. of Strands Transpos. pitch [mm] Filam. / strand I c (4.2K, s.f.) [A] per strand * extrapolated ** at 77 K Cable dimensions Width x hight [mm] (length [m] M.Leghissa Bi(2223) 1180** 13 3393 55 135** 9 x 2.5 (50) T. Hasegawa Bi(2212) 12000* 20 73 889 > 5000 11.35 x 1.9 (147) Bi(2212) 12000* 30 87 427 > 900 13.28 x 1.55 (300) S-C. Kim Bi(2212) 3146* 20 55 385 225* 8.26 x 1.46 (110) Bi(2212) 6960* 30 92 385 225* 12.39 x 1.46 (10) E.W.Collings Bi(2212) 3495 19 27.5 305 170 7.77 x 2.73 (5-10) RF BSCCO(2212)-cables exceeded 10 ka at lhe in self field! Long length was demonstrated (200 m) Cable upgrade (> factor 5) for high field specs. possible? Cable design and fabrication with low flexibility (reacted strand, Ag-sheath)? Is the wire an affordable, commercial product 30 26/27.05.2011 Wilfried Goldacker HTS4Fusion WS KIT
Conclusions It seems more promising to consider 2G HTS cables for application in Fusion technology Thanks for your attention! 31 26/27.05.2011 Wilfried Goldacker HTS4Fusion WS KIT